The following description relates generally to a data storage apparatus, an assembling method thereof and an apparatus for generating a tracking position error signal.
As emerging demands on media capable of storing large amounts of data have increased over the past years, researches and developments on increased storage capacity have been also on the rise. An SDS {SPM (Scanning Probe Microscope)-based Data Storage System}, which is an AFM (Atomic Force Microscopy)-method next generation large data storage system, has suddenly surfaced as a probe storage capable of replacing the future HDDs (Hard Disk Drives) and semiconductor memories due to its merits such as large storage capacity, small size and inexpensive cost.
When data is stored in the SDS, tracks must be searched and read with a precise resolution because bit size is around nano meter. For an accurate tracking, the conventional storage media like the HDDs use a PES (Position Error Signal), where a head is positioned to follow an accurate position of a track. The PES in the SDS is a signal indicating how far a cantilever tip for reading data is deviated from the track. FIGS. 1a, 1b and 1c are schematic views illustrating a PES generating method according to prior art, where servo pits are made on recording media by a cantilever tip to generate the PES. In other words, FIGS. 1a, 1b and 1c show how servo pits (A, B, C, D) are formed on respectively different positions of a recording medium, and the PESs are generated by the servo pits.
Referring first to FIG. 1a, a position of a servo pit ‘B’ is downshifted from a center of servo pit ‘A’ as far down as ‘d’, where the ‘d’ is a diameter. A position of a servo pit ‘C’ is downshifted from the center of the servo pit ‘A’ as much as d/2, and a P signal and a Q signal (which are PESs) generated from the servo pits are illustrated, where a track pitch (TP) is 3 d/2.
A track pitch (TP) in FIG. 1b is 3 d/2, which is the same as that of FIG. 1a, but a center of the serve pit ‘B’ is distanced from the center of servo pit ‘A’ as far as ‘TP-d’, while a center of the servo pit ‘C’ is distanced from the center of the servo pit ‘A’ as far as ‘TP/4’, which is the diameter. Therefore, the PESs generated from these servo pits are shown as the P signal and the Q signal.
Referring to FIG. 1c, a track pitch (TP) is 3 d/2, which is not same as that of FIGS. 1a and 1b, but the servo pits ‘A’ and ‘B’ are distanced as far as ‘TP/2’ and the center of the servo pit ‘C’ is positioned above from the center of servo pit ‘A’ as far as ‘TP/4’, which is the diameter. The PESs generated by these servo pits come to become more curved than what is illustrated in FIGS. 1a and 1b. 
The method of generating PESs suggested by the prior art suffers from a shortcoming that the PESs are generated by recording patterns of servo pits using cantilever tips after recording media are completely assembled to create an error of data storage on the recording media due to errors generated during recording of the servo pits. The method suffers from another shortcoming that process times are required for recording the servo pits for data storage.